The present invention applies to methods and apparatus for welding studs to railroad rail plates to which spring clip devices are attached to hold the rails in place and, more particularly, to such apparatus which is mobile and operates on the rails when in place to provide a retrofit for existing rails.
Railways have, for years, conventionally utilized wooden cross ties upon which are positioned rail plates under the railroad ties. The rail plates are anchored to the railroad ties by means of the conventional railway spikes. Additionally, the railway rail is secured to the railway plate by means of conventional railroad spikes.
The continual and repeated side loads upon the rails by the cars passing over the rails as well as other factors such as ice buildup under the rail flange ultimately cause the railway spikes to work upwardly from the rail tie. As this occurs, movement is permitted between the railway rail and the rail plate. This movement has the obvious disadvantage of permitting the rail to upset causing derailments. Additionally, the loose railroad spikes cannot control rail creep--i.e. longitudinal movement of the rail with respect to the rail plates.
In the past, various different forms of securing the rail to the rail plate have been tried such as threaded anchor bolts screwed into the railway tie and cooperating with spring clip members bearing against the rail flange. Additionally, other devices have been tried such as concrete ties into which there are cast anchor or securing devices which likewise cooperate with spring members to maintain the rail flange in engagement with the rail plate. In this latter case, replacement of the entire ties under an existing railway is expensive and thus, impractical.
The assignee of the present patent application, the KSM Division of Omark Industries, Inc., 301 New Albany Road, Moorestown, N.J. 08057, has developed a new spring clip rail retaining system. In the Omark system, a headed stud is welded to the rail plate on each side of the railroad rail. A spring retaining clip is engaged with the headed stud with a portion of the retaining clip bearing upon the flange or heal of the railroad rail. The stud-spring clip assembly provides flexure of the spring clip or a resiliency between the rail and the rail plate to overcome the foregoing described difficulties of railroad spikes.
One of the very significant advantages of the Omark system is that the studs and retaining clips can be a retrofit system to existing railways. The configuration of the studs is such that they can be welded between existing railway spikes on a given rail plate without the necessity of removing the railway spikes or replacing the rail plates and ties.
Apparatus for welding large headed studs to metallic base members such as railway plates has been known for considerable time. However, such apparatus is either a stationary machine located in a plant or a portable hand held welding gun. In the environment of welding studs to a railway rail plate, certain environmental difficulties are encountered. First, there must be four such studs welded to each of two rail plates for a given railway tie. The virtual number of studs which thus must be welded for a given section of railway track is enormous and the need for some apparatus to carry the studs and to automatically weld them becomes evident. Additionally, the supporting apparatus such as the welding generator and controllers must be capable of being moved along the rail conveniently.
A first consideration would be to mount the stud welding apparatus upon a railway car and move along the rails and weld two studs each side of each rail for a given railway tie simultaneously or substantially simultaneously and thus, move to the next rail and so on. However, there are many practical difficulties encountered in such an approach by reason of the physical variations in the railway system.
One significant variation is that the railroad ties are very often not absolutely perpendicular to the railroad rails. Thus, to align the welding guns to weld one set of headed studs for one railway plate will not necessarily align the other pair of welding gun assemblies in proper longitudinal relationship to the railway plate under the opposite rail. Likewise, variations in gage created by wear and displacement of the railway plates will create variations in the positioning of the railway assemblies for transverse welding position to the rail plate on a tie by tie basis.
A further yet difficulty encountered is obstructions which occur along the railway. One form of obstruction which may create interference conditions with the welding gun assemblies is the utilization of angle bars or couplings applied to the joints of the rails. Other forms of obstructions which give difficulties are railway spikes which have worked upwardly out of the tie to such a height as to cause an intereference.
A further yet variation which can create difficulty in an on site welding situation is the vertical distance between a given railway car and a rail as the railway car moves along the track. Deflection of the railroad rails upon loose ties, wear of the rail and the like will create a vertically varying distance betwen a welding gun and the rail which must be compensated for.